Hundreds of Marylanders may need spinal taps as public health leaders seek to rein in a fungal meningitis outbreak that continues to expand as more is learned about the unusual cases.

Health officials said Wednesday that they still are working to contact and evaluate those at risk of meningitis, an infection of the membranes that protect the brain and spinal cord. About 1,500 people in the state are among the 13,000 nationwide thought to have been exposed to the disease from spinal injections of a contaminated steroid.

New types of infections could start to crop up as officials explore cases in which patients may have received the tainted drug in other parts of the body for arthritis and other ailments. The Centers for Disease Control warned doctors Monday to be alert for such infections.

"We're asking doctors to have a high index of suspicion and a low threshold for treatment," said Dr. Lucy Wilson, chief of Maryland's infection prevention and outbreak response program.

If meningitiscases are identified early enough, the treatment can be effective, doctors said. Patients receive large, extended doses of intravenous antifungal medications.

However, the disease can be deadly, doctors said, because it occurs around the brain and prompts a strong immune response that can cause even more damage to the body.

In severe cases, patients may need to be hospitalized and treated with other medications for symptoms such as brain swelling, shock and seizures. In this outbreak, some patients also suffered strokes.

The dozen deaths — including one in Maryland — may have occurred because the initial cases weren't diagnosed fast enough, doctors said. Given the rarity of fungal meningitis and the unusual circumstances surrounding the outbreak, health officials aren't yet assuming that they have the situation figured out.

While 137 meningitis cases have been reported across the country, nine as of Wednesday in Maryland, some focus has shifted to how to treat the thousands of others who received the shots but are showing only mild symptoms, or none at all.

At Upper Chesapeake Health, about 50 patients have come in during the past five days concerned about meningitis risk, said Dr. Farheem Younus, chief of infectious diseases at the Harford County-based health system. All but five of them required spinal taps to test for the disease — an "unprecedented" number in such a short period, he said — and two of those tests showed some evidence of meningitis.

Three of the seven Maryland clinics that received the steroid are in Harford County.

A spinal tap, known in the medical field as a lumbar puncture, involves inserting a long needle into the lower back to collect a sample of spinal fluid. Health officials recommend the test for anyone who received a dose of the tainted steroid and are showing at least mild symptoms of meningitis, such as fever, a stiff neck and headache, Wilson said.

The test itself can cause headaches and nausea that can leave patients sick in bed for days, doctors said. Given that most of the patients were treated originally for back pain, it's not always an easy procedure, they said.

Most of those who received the tainted steroid shots have been reached, and federal and state health officials are working with doctors at the seven Maryland facilities that received shipments of the steroids to find the last few, Wilson said. In the meantime, health officials are monitoring emergency room patients' complaints and working closely with county health departments to detect any new cases, she said.

If the disease is allowed to develop and spread, the consequences to the brain can be significant, doctors said.

Because the fungus was injected directly into patients' spinal fluid, it is already behind defenses that keep toxic substances and organisms away from the brain, said Dr. Michael S. Donnenberg, a professor of microbiology and immunology, and associate chairman for research in the department of medicine at the University of Maryland School of Medicine.

In that environment, the fungus can grow and elicit a strong response from the immune system that could overwhelm the surrounding tissue, he said. The fungus and immune-response cells that respond to the outside invader can increase pressure and cause blood clots that block off parts of the brain. That can lead to blindness, deafness or destruction of parts of the brain that control other functions, and sometimes even death.

"We're well built to stop a small infection before it gets bad, but in a big or bad infection those same mechanisms that work really well can actually do a lot of damage," Donnenberg said.

It's also possible that hospitals could eventually see cases involving other types of infections, though none have been confirmed.

The contaminated medication, methylprednisolone, is like a liquid version of the common steroid prednisone, Perl said, and is used frequently to treat all types of pains, such as arthritic joints. If the fungus caused infections in those cases, patients could see redness or inflammation in joints, she said.

Health officials are "actively looking" for those types of cases in Maryland after some cases in other states raised suspicion, Wilson said. The incubation period for such infections may be longer than the one to four weeks for meningitis, she said.

While considered less dangerous than spinal meningitis, these infections could spread to other parts of the body and become more serious, she said.

Technicians at the Cape Apothecary compounding pharmacy in Annapolis spend their days mixing drugs that are no longer sold commercially or creating specialized batches of medicine for patients such as children who can't handle the normal dose.

BALTIMORE — Maryland health officials say three more residents have developed meningitis after receiving a steroid injection, bringing the total people who became ill in the state to eight. One person has died.

Maryland health officials said Monday that two more patients have developed meningitis in the state after receiving a steroid injection for back pain in an outbreak that has hit nearly two dozen states.

Josh Sanders, 33, sat in a chair in the corner of the cafeteria at Featherbed Lane Elementary, still in his work clothes, as his two daughters bounced from table to table, putting juice and snacks in a bag to take home.